Barack Obama calls Donald Trump's efforts to repeal Obamacare 'aggravating'

'It's certainly frustrating to have to mobilise every couple of months to keep our leaders from inflicting real human suffering on our constituents'

Former US President Barack Obama speaks at the Bill and Melinda Gates Foundation Goalkeepers event in Manhattan, New York (REUTERS/Elizabeth Shafiroff)

Barack Obama has called Donald Trump's repeated efforts to repeal Obamacare "aggravating."

Speaking at a summit hosted by billionaires Bill and Melinda Gates to coincide with the United Nations General Assembly, the former US President urged people not to be discouraged by unsteady progress as they work on pressing global issues.

He said the real problems facing the world "can't discourage any of us from the belief that individually and collectively, we can make a difference."

He spoke about some of his own frustrations after leaving office, including the battle over the Affordable Care Act.

The US President and Republican leaders in the US Senate are again pushing to repeal central elements of the law after repeated failures, with a vote possible next week.

"When I see people trying to undo that hard-won progress for the 50th or 60th time with bills that would raise costs or reduce coverage... it is aggravating," Mr Obama said.

"It's certainly frustrating to have to mobilise every couple of months to keep our leaders from inflicting real human suffering on our constituents."

Opponents of Mr Obama's health law to expand coverage for more Americans have criticised it as being costly and ineffective, arguing people shouldn't be forced to buy health insurance.

Discussing climate change, Mr Obama said the federal government wasn't "as engaged in these efforts as I would like."

Mr Trump has said he will pull out of the Paris climate change accord, an agreement the Obama administration worked with other countries to fashion.

But the response to setbacks, Mr Obama said, had to be "to reject cynicism and reject pessimism and push forward."

He said: "Rather than be daunted by those challenges, those challenges should inspire us and excite us because it gives us an opportunity to make our mark on the world."

Additional reporting by agencies